Red Hot Chili Peppers' bassist Flea did. The Australian-born rocker, who apparently is one of the gorilla’s favorites, got to hear Koko strum - or rather, try to strum - at the Gorilla Foundation in Woodside, California. The foundation posted a short video of their jam session, adding: "Koko rocks a flea bass like it ain't nuthin."

The Gorilla Foundation's development director Jane Narich told NBC Bay Area on Tuesday that it was really great having Flea come to the foundation — the rocker emailed that he wanted to play with Koko about six months ago, and his wish was granted.